Patrick kennedy



(No Model.)

. P. KENNEDY. POLE CHANGING MECHANISM FOR ELEGTRIG GENERATORS.

Patented Nov. 30,1897.

7 ATTORNEY UNITED STATES PATENT OFFICE.

PATRICK KENNEDY, OF BROOKLYN, NEYV YORK, ASSIGNOR TO THE AMERI- CAN RAILWAY ELECTRIC LIGHT COMPANY, OF NElV YORK, N. Y.

POLE-CHANGING MECHANISM FOR ELECTRIC GENERATORS.

SPECIFICATION forming part of Letters Patent No. 594,745, dated November 30, 1897.

Application filed April 26,1897. Serial No- 633,8'72. (N model.)

T0 on whom it may concern:

Be it known that I, PATRICK KENNEDY, a citizen of the United States, residing at Brooklyn, in the county of Kings and State of New York, have invented certain new and useful Improvements in Pole-Changing Mechanisms for Use in Connection with Generators of Electricity, of Which the following is a specification.

This invention relates to the class of automatic mechanism for preserving the signs of polarity in an external circuit fed by a dynamo when the direction of rotation of the armature of the dynamo is reversed, so that I 5 in whatever direction the armature may rotate the current in the external circuit will continue to flow in the proper direction.

One important application of the invention is in electric-lighting systems for cars,in which the generator is driven from an axle of the car and the latter is run indifferently with either end ahead.

The present invention comprises a simple and efficient automatic means whereby the 2 5 poles are changed through the medium of the change in the direction of rotation of the armature of the dynamo Whenever the direction of such rotation is reversed from any cause, and it includes also a novel form and c arrangement of the commutator-brushes and their holders, all as will be hereinafter de scribed.

In the accompanying drawings, which illustrate an embodiment of the invention,Figure 1 5 is a face View of the commutator-brushes and their holders as seen from the right in Fig. 2. This view shows the brushes in an intermediate inoperative position as in the act of shifting. Fig. 2 is a. side elevation of the I brushes and pole-changing mechanism. Fig. 3 is a plan of the mechanism seen in Figs. 1 and 2. Fig. 4 is a somewhat diagrammatic view of the brushes seen from the same point of view as in Fig. 1, but showing one pair of the 5 brushes in contact with the commutator.

Fig. 5 is an enlarged detail View of the shifting-helix. Fig. 6 is an enlarged detail view of the stud on the shifting-lever which plays in the grooves of the shifting-helix. Fig. 7

o is a dia rammatic View illustratin the a O l plication of the shifting mechanism to a polechanging switch instead of to the commutator-brushes.

Referring to the principal views, it may be said preliminarily that in the construction therein represented two pairs of brushes are employed, either pair of which may be put in contact at will with the commutator, said brushes being shifted at each change of direction in the rotation of the armature of the dynamo by mechanism between the brushes and the arbor of the armature.

1 is the armature. 2 is the commutator. 3 is a part of a fixed frame, and 8 is a bearingboss on said frame in which the arbor a of the armature is rotatively mounted. On the boss 3 is loosely mounted a ring or collar 5, which has projecting from it a stud or pin (5, which engages rather loosely (see Fig. 3) a hole in a link 7, which couples the collar 5 to one arm of a shifting-lever 9, fulcrumed on the fixed frame and carrying at its other end a stud 10, (seen detached in Fig. 6,) which engages the grooves in a shifting-helix 11. (Seen detached in Fig. 5.) This helix is fixed on a cross-shaft 12, mounted in bearings on the frame, and on it is fixed a worm-wheel 13, which gears with a worm or screw 14': (see Fig. 2) on a prolongation of the armaturc-arbor. Rapid rotation of the armature produces slower rotation of the helix 11 through the medium of the worm-gear described, and the direction of rotation of the helix will of course depend on that of the armature.

In order to make clear the function and operation of the helix 11, its peculiar construction will now be described with reference to Fig. 5, wherein letters are employed to designate the features of the helix. This helix is conveniently formed from a cylinder of metal in which are out near its respective ends two relatively shallow circumferential grooves a and b, and these are connected by IOO the holder 15.

10 (seen partly in section in Fig. 6,) which may slide on the stud and which is adapted to be pressed outwardly on the said stud by a spring 9*. To understand the operation, suppose the helix 11, Fig. 5, to be rotating in the direction of the arrow ,2 and the stud 10 to be in the circumferential groove a. As the helix rotates the stud will pass off the shoulder d at that end of the helix once in each rotation of the latter, the spring-actuated roller-sleeve10 thereon being protruded or pressed back to adapt the stud to the varying depths at different points in the groove. So long as rotation of the helix in this direction is maintained the stud 10 will travel in the groove a, but if the rotation of the helix be reversed the stud 10, or, rather, the sleeve 1O thereon, will engage the oblique shoulder d, be deflected into the helical groove 0, and carried by the rotation of the helix over to the circumferential groove 1), where it will remain until the rotation of the helix is again reversed, when it will be carried back again by the groove 0 to the groove a. The effect of this movement or travel of the stud 10 is to swing the shifting-lever 0 from side to side and through it to impart a rocking rotary movement to the collar 5 about the arbor of the armature.

The holders 15 of the commutator-brushes are pivotally mounted in couples on oppositely-arranged lugs or brackets 011 the collar 5, as clearly shown in Figs. 1 and 4, and each is supported on a roller-stud 16, mounted on the fixed frame 3, being held against the stud by a spring, that here shown being a wire spring 17 coiled about the pivotal stud, with its respective ends or branches bearing on the backs of the holders. In each holder 15 is secured a brush, the brushes designated by the numeral 1S constituting one pair and those designated by the numeral 18 constituting the other pair. On the inner face of each holder 15 is a cam 19, conveniently formed by increasing the width of the arm itself, and these cams have the effect to move the brushes carried by the arms out of contact with the commutator whenever by rotation of the sleeve 5 a cam is drawn over a stud 16. Fig. 1 shows a position of the sleeve 5 while the shifting of the brushes is being effected and when all of the brushes are out of contact, and Fig. 4 shows a terminal position where the brushes 1S are in contact with the commutator 2.

It will be noted that the brushes are not straight, but curved, the curvature corresponding to a radius equal to the length of The object of this construction is to cause the brush as it wears away from abrasion to maintain a substantially uniform bevel and also to maintain its pri mary place of contact with the commutator. This is quite important in a car-lighting system where the brushes should be adapted to regulate and care for themselves for considerable periods. If the angle at which the brush impinges upon the commutator constantly varies in such a way as to increase the bevel at its end, the brush soon deteriorates. A brush curved and mounted as herein shown will wear away very uniformly, the bevel slightly decreasing as the wear increases.

lVhere it is preferred to use but one pair of brushes and to change the poles by means of a switch, the device shown somewhat diagrammatically in Fig. 7 may be employed. In this figure, 2 represents the commutator, and 18 the brushes. Six contact-terminals arranged abreast are adapted to be put in contact with a forked switch-point 20, pivotally mounted in the usual manner. The contacts 21 and 22 are respectively the terminals or electrodes of the positive and negative brushes 18. The outer contacts 23 are con nected together electrically and form the positive terminal of the exterior circuit, and the inner contacts 24 are connected together electrically and form the negative terminal of the exterior circuit. As represented in Fig. 7, the right-hand branch of the switchpoint connects the negative-terminal contact 22 with the contact 24: at that side, and the left-hand branch of said switch-point connects the positive terminal 21 with the contact 23 at that side. Now if the switch point were shifted to the right it will be obvious by inspection that the signs of polarity in the outer circuit would be changed, but as the switch-point will be shifted only when the direction of rotation of the armature is reversed, and in consequence the signs of polarity at the brushes 18 changed, it will be obvious that the signs in the exterior circuit will remain constant while those at the brushes change. In Fig. 7 the same mechanism is shown for shifting the switch-point 20 as that shown in the principal views for shifting the collar 5that is to say, the shifting-lever 9 is coupled at one end to the switchpoint by a link 7, and the helix 11 and wormgearing are the same and perform the same functions as those before described.

In Fig. 2 the worm-wheel 13 is not fully shown in full lines, but it is clearly shown in Fig. 3.

In Fig. 4.- the field-magnets are indicated diagrammatically.

WVhile the invention described is especially well adapted for use in car-lighting systems, nevertheless it may be employed in any case where the polarity of the exterior circuit is to remain constant and the direction of rotation of the armature is subject to variation.

Having thus described my invention, I claim 1. The combination with a dynamo, of a shifting helix, having two relatively shallow circumferential grooves and a deeper, spiral groove, connecting said two circumferential grooves and forming deflecting shoulders at the points of intersection therewith, a shift ing-lever, having a stud which engages a groove in said helix, gearing between the armature of the dynamo and said helix, whereby the former rotates the latter, and a polechanger connected with and adapted to be operated by said shifting-lever when the direction of rotation of the dynamo is reversed.

2. The combination with a dynamo, having a rotating armature and a commutator, of a shifting helix having two relatively shallow circumferential grooves and a deeper spiral groove connecting said circumferential grooves, substantially as described, gearing between the armature and said helix whereby the former rotates the latter, a shifting-lever provided with a stud which engages a groove in said helix, two pairs of movably-mounted commutator-brushes, either pair of which may be put in contact with the commutator at will, and connections between said brushes and said shifting-lever, whereby the latter shifts the brushes when the direction of rotation of the armature is changed.

The combination with a dynamo having a rotating armature and a commutator, of the movable ring or sleeve 5, the brush-holders 15, pivotally mounted on said sleeve and having each a cam 19, the studs 16, over which said cams are drawn when said sleeve is moved rotatively, the brushes carried by the respective holders, the springs which serve to keep the brushes pressed up toward the commutator, and shifting mechanism between said sleeve 5 and the armature adapted to shift the brushes by a rotative movement of said sleeve when the direction of rotation of the armature is changed.

4. In a pole-changing mechanism, the combination with the shifting helix 11, having circumferential grooves CL and b, a deeper spiral groove 0, connecting the said circumferential grooves, and deflecting shoulders (Z, (Z, as described, of the shifting-lever 9, having a fixed stud 10, a sliding sleeve 10*, on said stud, and a spring 9 bearing 011 said sleeve, said sleeve and stud engaging a groove in said helix, substantially as and for the purpose set forth.

In witness whereof I have hereunto signed my name in the presence of two subscribing witnesses.

PATRICK KENNEDY.

lVitnesses PETER A. Boss, HENRY CONNETT. 

